The present invention relates to an image processing apparatus and method, which are applied to entrance/exit management of an important facility, or access management of a computer (terminal device) and are suitably applied to a personal authentication apparatus for authenticating a person on the basis of vital information (biometrics) such as a facial image.
In recent years, in view of application to a human interface, security, and the like, a personal authentication technique based on vital information (biometrics) such as a facial image, or the like is becoming increasingly important, and various techniques have been developed.
As biometrics, fingerprints, palmprints, voiceprints, and signature verifications, retina and iris scans, and the like are put into practical use. These schemes are categorized into “contact type” a person must directly touch a device, and “non-contact type” a person need not touch.
Of the above examples of biometrics, fingerprints, palmprints, and signature verifications belong to “contact type”. However, the category of signature verifications is slightly different from that of fingerprint verification and the like since a signature verification requires a person to take an action, i.e., to sign.
Biometric that similarly requires person's action is voiceprint (speech) verification, but it belongs to “non-contact type”. Retina and iris scans belong to “non-contact type” since a camera captures an image of a desired portion and the captured image is processed. However, since a retina is located at the bottom of an eyeball and must be scanned while the eye nearly contacts a lens, its category is close to “contact type”.
Note that the iris is present on the surface of the eyeball, and can be scanned by a camera at a separate position. However, since a micropattern must be scanned, the maximum distance between the eye and camera is naturally limited.
On the other hand, facial image verification as non-contact biometric has received a lot of attention recently, and various techniques using this have been developed. A facial pattern has a larger scale than the aforementioned iris pattern.
In a personal authentication apparatus that adopts facial image verification, one monitor camera is set at an appropriate position to capture a facial image of a full-face or nearly full-face pose, and the captured image undergoes pattern verification with facial image data registered in advance under similar conditions.
Also, a system in which a camera is set at a relatively lower position to capture a looked-up facial image and to register and verify it has been proposed.
For example, Jpn. Pat. Appln. KOKAI Publication No. 11-196398 discloses a technique that pertains to an image processing apparatus in which video cameras are laid out to make a given angle, a facial image of a full-face pose is stored in a full-face template memory, a facial image of a left-half-face pose is stored in a half-face template memory, and the correlation between images output from the video cameras and data stored in the memories is computed to determine the facial motion of a person (to be referred to as prior art 1 hereinafter).
Furthermore, Fukui and Yamaguchi, “Facial Feature Point Extraction by Combining Shape Extraction and Pattern Verification”, Journal of IEICE (D-II), Vol. j-80-D-II, No. 8, August 1997, proposes a method of extracting facial feature points of a pupil, nasal cavity, mouth edge, and the like from a moving image at high speed and high precision for facial recognition (to be referred to as prior art 2 hereinafter).
Also, Yamaguchi, Fukui, and Maeda, “Facial Recognition System Using Moving Image”, IEICE Transactions PRMU97-50, June 1997, proposes a personal identification method for facial recognition using a moving image (time-series images) in place of a single image (to be referred to as prior art 3 hereinafter).